The present invention relates to an electric toothbrush.
Electric toothbrushes utilize an electric motor to drive a brush head to provide a brushing action for cleaning teeth. One such toothbrush is disclosed by Sham in U.S. Pat. No. 5,822,821. Sham discloses an electric toothbrush having a motor, which drives a driven gear. The driven gear drives a crank member. The crank member, in turn drives a reciprocating rocker arm. The rocker arm, in turn, drives a brush head. The rate of rotation of the driven gear in the device determines the frequency of reciprocation of the brush head, while the length and shape of the crank member determine the angular sweep and the average angular speed of the brush head.
The present invention is directed to an electric toothbrush, comprising a housing, an electric motor, a first transmission and a second transmission. The electric motor is linked to the housing, and drives a motor output member for rotation about a motor output axis. The first transmission is linked to the motor output member and converts rotational movement from the motor output member into rotational reciprocating movement at a first average angular speed and along a first angular sweep. The second transmission is linked to the first transmission and converts rotational reciprocating movement from the first transmission into rotational reciprocating movement at a second average angular speed about a second transmission output axis that is parallel to the first axis, and along a second angular sweep. The second transmission drives an output member to reciprocate at the second average angular speed about the second transmission output axis, and along the second angular sweep. The second transmission can include first and second gear members. The first gear member can include a section of an internal gear connected to the first transmission. The second gear member is drivenly connected to the first gear member and comprises a spur gear. The output member can include a removably attachable brush head.